diff --git a/sys/arch/x86/include/bus_private.h b/sys/arch/x86/include/bus_private.h
index ce2b9264aa6e..954e24d22de4 100644
--- a/sys/arch/x86/include/bus_private.h
+++ b/sys/arch/x86/include/bus_private.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: bus_private.h,v 1.1 2005/04/16 08:53:09 yamt Exp $	*/
+/*	$NetBSD: bus_private.h,v 1.2 2005/08/20 19:18:11 bouyer Exp $	*/
 /*	NetBSD: bus.h,v 1.8 2005/03/09 19:04:46 matt Exp	*/
 
 /*-
@@ -98,12 +98,12 @@ void	_bus_dmamem_unmap(bus_dma_tag_t tag, caddr_t kva, size_t size);
 paddr_t	_bus_dmamem_mmap(bus_dma_tag_t tag, bus_dma_segment_t *segs,
 	    int nsegs, off_t off, int prot, int flags);
 
+#ifndef _PRIVATE_BUS_DMAMEM_ALLOC_RANGE
 int	_bus_dmamem_alloc_range(bus_dma_tag_t tag, bus_size_t size,
 	    bus_size_t alignment, bus_size_t boundary,
 	    bus_dma_segment_t *segs, int nsegs, int *rsegs, int flags,
-	    paddr_t low, paddr_t high);
-
-
+	    bus_addr_t low, bus_addr_t high);
+#endif
 
 /*
  * Cookie used for bounce buffers. A pointer to one of these it stashed in
@@ -173,4 +173,13 @@ _bus_virt_to_bus(struct pmap *pm, vaddr_t va)
 }
 #endif /* !defined(_BUS_VIRT_TO_BUS) */
 
+/*
+ * by default, the end address of RAM visible on bus is the same as the
+ * largest physical address.
+ */
+#ifndef _BUS_AVAIL_END
+#define _BUS_AVAIL_END (avail_end)
+#endif
+
+
 #endif /* !defined(_X86_BUS_PRIVATE_H_) */
diff --git a/sys/arch/x86/x86/bus_dma.c b/sys/arch/x86/x86/bus_dma.c
index c0ab6d890e06..a4ca2acbb42b 100644
--- a/sys/arch/x86/x86/bus_dma.c
+++ b/sys/arch/x86/x86/bus_dma.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: bus_dma.c,v 1.21 2005/04/16 07:53:35 yamt Exp $	*/
+/*	$NetBSD: bus_dma.c,v 1.22 2005/08/20 19:18:11 bouyer Exp $	*/
 
 /*-
  * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
@@ -38,7 +38,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 1.21 2005/04/16 07:53:35 yamt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bus_dma.c,v 1.22 2005/08/20 19:18:11 bouyer Exp $");
 
 /*
  * The following is included because _bus_dma_uiomove is derived from
@@ -139,6 +139,68 @@ static int _bus_dmamap_load_buffer(bus_dma_tag_t t, bus_dmamap_t map,
 static __inline int _bus_dmamap_load_busaddr(bus_dma_tag_t, bus_dmamap_t,
     bus_addr_t, int);
 
+#ifndef _PRIVATE_BUS_DMAMEM_ALLOC_RANGE
+#define _PRIVATE_BUS_DMAMEM_ALLOC_RANGE _bus_dmamem_alloc_range
+
+/*
+ * Allocate physical memory from the given physical address range.
+ * Called by DMA-safe memory allocation methods.
+ */
+int
+_bus_dmamem_alloc_range(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
+    bus_size_t boundary, bus_dma_segment_t *segs, int nsegs, int *rsegs,
+    int flags, bus_addr_t low, bus_addr_t high)
+{
+	paddr_t curaddr, lastaddr;
+	struct vm_page *m;
+	struct pglist mlist;
+	int curseg, error;
+
+	/* Always round the size. */
+	size = round_page(size);
+
+	/*
+	 * Allocate pages from the VM system.
+	 */
+	error = uvm_pglistalloc(size, low, high, alignment, boundary,
+	    &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
+	if (error)
+		return (error);
+
+	/*
+	 * Compute the location, size, and number of segments actually
+	 * returned by the VM code.
+	 */
+	m = mlist.tqh_first;
+	curseg = 0;
+	lastaddr = segs[curseg].ds_addr = VM_PAGE_TO_PHYS(m);
+	segs[curseg].ds_len = PAGE_SIZE;
+	m = m->pageq.tqe_next;
+
+	for (; m != NULL; m = m->pageq.tqe_next) {
+		curaddr = VM_PAGE_TO_PHYS(m);
+#ifdef DIAGNOSTIC
+		if (curaddr < low || curaddr >= high) {
+			printf("vm_page_alloc_memory returned non-sensical"
+			    " address 0x%lx\n", curaddr);
+			panic("_bus_dmamem_alloc_range");
+		}
+#endif
+		if (curaddr == (lastaddr + PAGE_SIZE))
+			segs[curseg].ds_len += PAGE_SIZE;
+		else {
+			curseg++;
+			segs[curseg].ds_addr = curaddr;
+			segs[curseg].ds_len = PAGE_SIZE;
+		}
+		lastaddr = curaddr;
+	}
+
+	*rsegs = curseg + 1;
+
+	return (0);
+}
+#endif /* _PRIVATE_BUS_DMAMEM_ALLOC_RANGE */
 
 /*
  * Create a DMA map.
@@ -186,7 +248,7 @@ _bus_dmamap_create(bus_dma_tag_t t, bus_size_t size, int nsegments,
 
 	*dmamp = map;
 
-	if (t->_bounce_thresh == 0 || avail_end <= t->_bounce_thresh)
+	if (t->_bounce_thresh == 0 || _BUS_AVAIL_END <= t->_bounce_thresh)
 		map->_dm_bounce_thresh = 0;
 	cookieflags = 0;
 
@@ -791,14 +853,14 @@ _bus_dmamem_alloc(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
     bus_size_t boundary, bus_dma_segment_t *segs, int nsegs, int *rsegs,
     int flags)
 {
-	paddr_t high;
+	bus_addr_t high;
 
-	if (t->_bounce_alloc_hi != 0 && avail_end > t->_bounce_alloc_hi)
+	if (t->_bounce_alloc_hi != 0 && _BUS_AVAIL_END > t->_bounce_alloc_hi)
 		high = trunc_page(t->_bounce_alloc_hi);
 	else
-		high = trunc_page(avail_end);
+		high = trunc_page(_BUS_AVAIL_END);
 
-	return (_bus_dmamem_alloc_range(t, size, alignment, boundary,
+	return (_PRIVATE_BUS_DMAMEM_ALLOC_RANGE(t, size, alignment, boundary,
 	    segs, nsegs, rsegs, flags, t->_bounce_alloc_lo, high));
 }
 
@@ -1133,61 +1195,3 @@ _bus_dmamap_load_buffer(bus_dma_tag_t t, bus_dmamap_t map, void *buf,
 	return (0);
 }
 
-/*
- * Allocate physical memory from the given physical address range.
- * Called by DMA-safe memory allocation methods.
- */
-int
-_bus_dmamem_alloc_range(bus_dma_tag_t t, bus_size_t size, bus_size_t alignment,
-    bus_size_t boundary, bus_dma_segment_t *segs, int nsegs, int *rsegs,
-    int flags, paddr_t low, paddr_t high)
-{
-	paddr_t curaddr, lastaddr;
-	struct vm_page *m;
-	struct pglist mlist;
-	int curseg, error;
-
-	/* Always round the size. */
-	size = round_page(size);
-
-	/*
-	 * Allocate pages from the VM system.
-	 */
-	error = uvm_pglistalloc(size, low, high, alignment, boundary,
-	    &mlist, nsegs, (flags & BUS_DMA_NOWAIT) == 0);
-	if (error)
-		return (error);
-
-	/*
-	 * Compute the location, size, and number of segments actually
-	 * returned by the VM code.
-	 */
-	m = mlist.tqh_first;
-	curseg = 0;
-	lastaddr = segs[curseg].ds_addr = VM_PAGE_TO_PHYS(m);
-	segs[curseg].ds_len = PAGE_SIZE;
-	m = m->pageq.tqe_next;
-
-	for (; m != NULL; m = m->pageq.tqe_next) {
-		curaddr = VM_PAGE_TO_PHYS(m);
-#ifdef DIAGNOSTIC
-		if (curaddr < low || curaddr >= high) {
-			printf("vm_page_alloc_memory returned non-sensical"
-			    " address 0x%lx\n", curaddr);
-			panic("_bus_dmamem_alloc_range");
-		}
-#endif
-		if (curaddr == (lastaddr + PAGE_SIZE))
-			segs[curseg].ds_len += PAGE_SIZE;
-		else {
-			curseg++;
-			segs[curseg].ds_addr = curaddr;
-			segs[curseg].ds_len = PAGE_SIZE;
-		}
-		lastaddr = curaddr;
-	}
-
-	*rsegs = curseg + 1;
-
-	return (0);
-}